The lateral superior olivary nucleus (LSO) is an auditory relay centre within the brain stem that encodes interaural level differences for sound localization by integrating GABA/glycinergic input from the contralateral ear via the medial nucleus of the trapezoid body (MNTB), and glutamatergic input from the ipsilateral ear via the ventral cochlear nucleus (VCN). 
The lateral superior olivary nucleus was characterized by a distinct nuclear shape.
In this study, CB-immunohistochemistry was used to examine 1-42 postnatal-day-old kitten and adult cat CNIC and anterograde tracers were used to label afferent projections from the lateral superior olivary nucleus (LSO) to the CNIC at similar ages.
A group of central auditory neurons residing in the lateral superior olivary nucleus (LSO) responds selectively to interaural level differences and may contribute to sound localization.
The largest group of OC neurons was comprised by small, intrinsic lateral OC neurons within the ipsilateral lateral superior olivary nucleus (LSO), almost all of which (97%) were located ipsilaterally.
Glycinergic transmission shapes the coding properties of the lateral superior olivary nucleus (LSO).
For instance, both convulsing agents decreased the amplitude and increased the latency of P4, that is the wave component of the ABRs generated in the lateral superior olivary nucleus and while PTZ increased the latency of P3, the wave component of the ABRs generated in the medial superior olivary nucleus, 4-AP dramatically increased its amplitude.
The lateral superior olivary nucleus lacked a distinct nuclear shape but was formed by several patches of rather irregularly arranged neurons.
In the auditory system, inhibitory transmission from the medial nucleus of the trapezoid body (MNTB) to neurons of the lateral superior olivary nucleus (LSO) undergoes activity-dependent long-term depression, and may be associated with developmental elimination of these synapses [ Sanes DH, Friauf E (2000).
Optical density (OD) measurements were made from individual neurons in the anteroventral cochlear nucleus (AVCN) and from medial and lateral dendritic fields in the medial superior olivary nucleus (MSO), the lateral superior olivary nucleus, and the inferior colliculus.
The initial processing of interaural intensity differences (IIDs), the major cue to the azimuthal location of high-frequency sounds in mammals, is carried out by neurons in the lateral superior olivary nucleus (LSO) that receive excitatory input from the ipsilateral ear and inhibitory input from the contralateral ear (IE neurons).
Stained terminals were observed mainly in the lateral superior olivary nucleus and in the superior paraolivary nucleus.
In the rat, the former is constituted by neurons located in the lateral superior olivary nucleus, that project to the inner hair cells, while the later originates in the ventral nuclei of the trapezoid body and project to the outer hair cells.
Of particular interest is the stark contrast between high level expression of Kv1.1 and very low level expression of Kv3.1 in the octopus cell area of the cochlear nucleus and in the lateral superior olivary nucleus.
The comparison with retrogradely labeled neurons showed that perikarya in the lateral superior olivary nucleus and, in particular, the medial nucleus of the trapezoid body were double-labeled.
Of these, the majority (mean 787) were small, lateral olivocochlear neurons found almost exclusively within the ipsilateral lateral superior olivary nucleus.
In accordance with the literature, we observed neurons innervating the IC located in the lateral superior olivary nucleus (LSO) and dorsal periolivary groups (DPO) on both sides, in the superior paraolivary nucleus (SPO) predominantly ipsilateral, as well as in the ipsilateral medial superior olivary nucleus (MSO) and the medial nucleus of the trapezoid body (MNTB).
Neurons in the lateral superior olivary nucleus (LSO) respond to acoustic stimuli with the "chopper response", a regular repetitive firing pattern with a short and precise latency.
The medial nucleus of the trapezoid body (MNTB) is one of three major nuclei of the superior olivary complex and provides an important inhibitory input from the contralateral ear to the lateral superior olivary nucleus (LSO) in the initial binaural pathway for coding interaural intensity differences.
Perikarya stained by either method were found in the medial nucleus of the trapezoid body and in periolivary nuclei projecting to the cochlea, while terminals were observed mainly in the lateral superior olivary nucleus and in the superior paraolivary nucleus.
In the brainstem, neurons in the lateral superior olivary nucleus and the anteroventral cochlear nucleus are transiently 5-HT immunolabeled.
The present report of calcium-binding proteins in the developing and adult superior olivary complex shows distinct distribution patterns for parvalbumin, calbindin, and calretinin in the lateral superior olivary nucleus (LSO) of the developing ferret that correspond to distribution patterns for different projection cell types and neurotransmitters.
Injections of fluorogold restricted to the granule cell layer retrogradely labeled neurons in the ipsilateral lateral superior olivary nucleus, in the periolivary region predominantly contralaterally, and in the inferior colliculus predominantly ipsilaterally.
The immunostaining in the medial and lateral superior olivary nuclei was observed as perineuronal nets around large principal neurons at the light-microscopic level, while no immunostaining was observed in the upper segment of the medial superior olivary nucleus and the medial segment of the lateral superior olivary nucleus, in which medium-sized and small neurons were located.
The projections of lateral olivocochlear neurons (LOC), which terminate beneath inner hair cells (IHCs), were investigated by injecting biotinylated dextran amine into the lateral superior olivary nucleus (LSO) and the surrounding region in the rat.
Nerve fibres and varicosities showing positive immuno-reactivity for both peptides were particularly dense immediately dorsal and lateral to the lateral superior olivary nucleus (LSO) and dorsal to the superior paraolivary nucleus (SPN).
In contrast, calbindin D28k immunoreactivity levels by this time were higher in deafferented neurons of the medial nucleus of the trapezoid body and their axons in the lateral superior olivary nucleus (LSO).
D beta H-positive cell bodies were found in the region of the ventral lateral lemniscus and immediately lateral and dorsal to the lateral superior olivary nucleus.
A comparable population of cells in the ipsilateral lateral superior olivary nucleus was retrogradely labeled in cases with unilateral injections of tritiated glycine in the inferior colliculus. In postnatal ferrets, immunopositive cell bodies were first observed by postnatal day 7 and were distributed in regions comparable to regions in the adult, with the exception that immunopositive cells in the lateral superior olivary nucleus did not appear until about postnatal day 28.
Collateral projections of gamma-aminobutyric acid (GABA) neurons from the lateral superior olivary nucleus (LSO) to the cochlea and cochlear nuclei in the guinea pigs were studied by injection of two retrograde fluorescent neuronal tracers.
Retrograde tracing by fluorogold combined with GAL immunohistochemistry demonstrated that, except for the cells of the contralateral lateral superior olivary nucleus (LSO), GAL-IR neurons project into the lesioned labyrinth..
The laterality of projections from the lateral superior olivary nucleus (LSO) to the inferior colliculus was studied in adult and immature postnatal ferrets.
CGRP-IR fibers in the cochlea originated in the ipsilateral lateral superior olivary nucleus.
The effects of a reduction during development of excitatory and inhibitory synaptic input on CNS neurones were studied in the lateral superior olivary nucleus (LSO) of the ferret following neonatal, unilateral cochlear removal.
The dendritic morphology of cells in the lateral superior olivary nucleus was studied with the Golgi method in adult and postnatal ferrets. The lateral superior olivary nucleus in the adult ferret is a convoluted structure with an M-shape in frontal sections.
In the present study, neuron counts were done on three key nuclei of the SOC: the medial nucleus of the trapezoid body (MNTB), the lateral superior olivary nucleus (LSO), and the medial superior olivary nucleus (MSO) in groups of Fischer 344 rats aged 3, 12, 24, and 30 months.
Particularly prominent are the neurons of the magnocellular division of the red nucleus, the large cells in the deep cerebellar nuclei and the vestibular nuclei and neurons of the lateral superior olivary nucleus.
Principal cells of the lateral superior olivary nucleus (LSO) are thought to receive a direct excitatory input from spherical bushy cells located in the ipsilateral ventral cochlear nucleus (VCN) and an indirect input from the contralateral VCN globular bushy cells via a secure synapse in the medial nucleus of the trapezoid body (MNTB).
The inputs to the EI region originate primarily from the dorsal nucleus of the lateral lemniscus (DNLL) and lateral superior olivary nucleus (LSO) bilaterally and from the ipsilateral INLL.
Areas examined included the dorsal and ventral cochlear nuclei which receive the primary afferents from the organ of Corti, the lateral superior olivary nucleus which has strong reciprocal relationships with the cochlear nucleus, and the successively more rostral projections of the auditory pathways to inferior colliculus, medial geniculate and auditory cortex.
The largest difference in 2-DG uptake between long- and short-term habituated rats was in the lateral superior olivary nucleus (LSO).
Differences between the newborn and adult were a slight but significantly greater number of bilaterally-projecting cells in the newborn, and the presence in the newborn of a small number of cells located in the lateral superior olivary nucleus contralateral to their target cochlea.
Of HRP-labeled nerve cells found in the brainstem, about 60% and 10% were located in the ipsilateral lateral superior olivary nucleus (LSO) and the contralateral ventral nucleus of the trapezoid body (VTB), respectively.
Labeled neurons were localized in the lateral superior olivary nucleus (LSO) and ventral nucleus of the trapezoid body (VNTB).
After 6 to 13 weeks, consistent with functional neuroanatomy of central auditory regions, incorporation was reduced by 6 to 9% in the left cochlear nucleus and left lateral superior olivary nucleus, compared with corresponding right-side regions.
Most labeled neurons were found in the ipsilateral lateral superior olivary nucleus (LSO), although both ventral nuclei of the trapezoid body (VTB), group E, and the caudal pontine reticular nucleus (CPR) just adjacent to the ascending limb of the facial nerve also contained labeled cells.
Injection of [ 3H]-gamma aminobutyric acid (GABA) into the perilymphatic space of the rat's inner ear resulted in retrograde labeling of a portion of the small efferent olivocochlear neurons within the lateral superior olivary nucleus (LSO).
In this study the organization of the projection from the lateral superior olivary nucleus (LSO) to the inferior colliculus was investigated in the cat by using anterograde tract-tracing techniques.
In the cat, immunoreactive neurons in the brainstem are located in the hilus of the lateral superior olivary nucleus and around its margins. In the rat, immunoreactive neurons are located within the lateral superior olivary nucleus proper.
The INT neurons formed a thin shell over the lateral superior olivary nucleus (LSO) and their dendrites extended into the body and hilar region.
Significant binding was observed in the anteroventral cochlear nucleus, the dorsal cochlear nucleus, the lateral superior olivary nucleus, and the inferior colliculus.
Five morphologically distinct classes of neurons can be identified within the neuropil of the gerbil lateral superior olivary nucleus (LSO) by using a variety of histological techniques and electron microscopy.
Twenty-four hours after cochlear perfusion with D-ASP, labeled neurons were observed in the ipsilateral, and to a much lesser extent in the contralateral, lateral superior olivary nucleus (LSO).
However, the total number of neurones found (mean of 1234 projecting to each cochlea) was significantly greater than that reported using horseradish peroxidase, largely as a result of more small labelled neurones being detected within the lateral superior olivary nucleus ipsilateral to the injected cochlea.
DYN B cell bodies were present in nonpyramidal cells of neo- and allocortices, medium-sized cells of the caudate-putamen, nucleus accumbens, lateral part of the central nucleus of the amygdala, bed nucleus of the stria terminalis, preoptic area, and in sectors of nearly every hypothalamic nucleus and area, medial pretectal area, and nucleus of the optic tract, periaqueductal gray, raphe nuclei, cuneiform nucleus, sagulum, retrorubral nucleus, peripeduncular nucleus, lateral terminal nucleus, pedunculopontine nucleus, mesencephalic trigeminal nucleus, parabigeminal nucleus, dorsal nucleus of the lateral lemniscus, lateral superior olivary nucleus, superior paraolivary nucleus, medial superior olivary nucleus, ventral nucleus of the trapezoid body, lateral dorsal tegmental nucleus, accessory trigeminal nucleus, solitary nucleus, nucleus ambiguus, paratrigeminal nucleus, area postrema, lateral reticular nucleus, and ventrolateral region of the reticular formation.
Like the medial superior olivary nucleus, the lateral superior olivary nucleus receives inputs from AA and APD. In addition, the lateral superior olivary nucleus receives projections from the posterior subdivision (AP) of the anterior division and also from the posterior division of the anteroventral cochlear nucleus. The projections to the medial superior olivary nucleus are bilateral, whereas the projections to the lateral superior olivary nucleus are almost entirely ipsilateral. One implication of the results is that the medial superior olivary nucleus receives inputs from only one cell type--the spherical bushy cell--but that, at the least, two cell types project to the lateral superior olivary nucleus.
After injection of biotin-wheat germ agglutinin (b-WGA) into the cochlea, CGRPI neurons in the ipsilateral lateral superior olivary nucleus also contained b-WGA granules.
Small neurons from the lateral superior olivary nucleus project to the inner hair cell area in a predominantly homolateral fashion, making almost exclusively synaptic contacts with the afferent dendrites associated with the inner hair cells.
Previous studies suggest that the principal cells of the medial nucleus of the trapezoid body (MNTB) give rise to the projection from MNTB to the lateral superior olivary nucleus (LSO) of the same side, where they mediate rapid inhibitory effects of contralateral sound stimulation.
After wheat-germ agglutinin-horseradish peroxidase injections in the lateral superior olivary nucleus anterograde label was observed bilaterally in the medial superior olivary nuclei.
Large numbers of small labelled neurones were found within the body of the lateral superior olivary nucleus (LSO) ipsi-lateral to the injected cochlea.
The synaptic organization of the lateral superior olivary nucleus of the cat was analyzed under the electron microscope.
Moreover, an extremely large population of labeled cells occurred within the cell mass of the lateral superior olivary nucleus (LSO) ipsilaterally to the injection site.
The largest concentration of HRP-labelled cells was usually observed in the ipsilateral superior olivary nucleus. Topographic organisation of the pathways ascending to the colliculus was expressed in the cochlear nuclei, lateral superior olivary nucleus and in the dorsal nucleus of the lateral lemniscus.
An indistinct dorso-lateral nucleotopic projection was found between the lateral superior olivary nucleus and the central nucleus.
Lesions of the lateral portion of the pons adjacent to the lateral superior olivary nucleus were accompanied by attenuation of P4 to ipsilateral input.
Additionally, the effects of the lesions on enzyme activities in the lateral superior olivary nucleus and ventral nucleus of the trapezoid body, and in the facial, motor trigeminal, and spinal trigeminal nuclei were examined.
The present study seeks to identify neurotransmitters mediating binaural inhibition in lateral superior olivary nucleus neurons. These findings suggest that glycine may be a neurotransmitter mediating binaural inhibition in certain SOC neurons and that the projection to the lateral superior olivary nucleus from the medial nucleus of the trapezoid body may be glycinergic..
Nine neuronal types were significantly smaller (P less than 0.01) on the left side: spiral ganglion neurons; globular, small spherical, large spherical, octopus, multipolar, and granule cells of the ventral cochlear nucleus; Purkinje-like cells of the dorsal cochlear nucleus; and spindle cells of the lateral superior olivary nucleus.
About 40% of the total number of labeled neurons, a remarkable quantity, occurred in the ipsilateral lateral superior olivary nucleus.
The highest metabolic effects were seen in the dorsal cochlear nucleus, the lateral superior olivary nucleus, and in the inferior colliculus.
In the lateral trapezoid nucleus peak production time is day E12; in the medial superior olivary nucleus, day E13; in the medial trapezoid nucleus, day E15; and in the lateral superior olivary nucleus, day E16. These mirror-image gradients were also seen intranuclearly in the lateral superior olivary nucleus and the medial trapezoid nucleus. The cytogenetic gradients could not be related to tonotopic representation; however, they could be related to the lateral location of ipsilateral cochlear nucleus input to the lateral superior olivary nucleus and the medial location of the contralateral cochlear nucleus input to the medial trapezoid nucleus..
Thus, although it is suggested that axons of DAS terminate preferentially in the ventro-lateral aspect of the contralateral ICC, it is likely that at least some neurones in this latter region receive additional input from another source - possibly the lateral superior olivary nucleus..
The lateral superior olivary nucleus was evenly labeled bilaterally while among the periolivary nuclei the dorsomedial periolivary nucleus was heavily labeled ipsilateral to the injection side.
Labeled axons entering the trapezoid body (TB) projected ipsilaterally to: (1) the lateral trapezoid nuclei (LTN), (2) the lateral superior olivary nucleus (LSO), (3) the dorsal dendritic zone of the medial superior olivary nucleus (MSO), and (4) the pericollicular or cortical nucleus of the inferior colliculus (IC).
A topically arranged projection was demonstrated from the nucleus of the trapezoid body (NTB) to the ipsilateral lateral superior olivary nucleus (LSO) wiht a lesser connection in the opposite direction.
HRP-positive cells were found in ipsilateral and contralateral lateral superior olivary nucleus (LSO), ipsilateral medial superior olivary nucleus (MSO), ipsilateral and contralateral lateral nucleus of the trapezoid body (LTB), ipsilateral ventral nucleus of the trapezoid body (VTB), and ipsilateral superior paraolivary nucleus (SPN).
Following injection of tracer into the muscle, labeled neurons were observed in the interface between the facial nerve nucleus and the caudal end of the lateral superior olivary nucleus.
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